Solid delivery systems provide effective and convenient treatment of the toilet bowl water through the use of slow dissolving blocks containing the desired cleaning ingredients. Solid blocks are extremely cost effective and typically contain materials to control dissolution. A variety of approaches have been used to control the release. The actives can be selected to have the desired limited solubility as in U.S. Pat. No. 4,820,449, Menke et al. or the actives can be incorporated into a microporous resin, as in U.S. Pat. No. 4,252,785, Isoldi.
Long-chain cellulosic polymers have been used as a major solid component to control dissolution and release of the active ingredients into the pooled water. For example, Barford et al., U.S. Pat. No. 4,269,723 teaches the use of water soluble, water dispersible clays and cellulosics to retard dissolution. Barford makes mention of chemically modified celluloses such as ethyl cellulose, methyl cellulose, sodium carboxymethyl cellulose, ethyl hydroxyethyl cellulose, and the like. Barford, et al., discloses a process for making lavatory cleansing blocks by tableting a free flowing particulate mix consisting essentially of, on a weight basis, from 5% to 90% of a surface active component and from 0.5% to 75% of one or more binders selected from clays and water soluble or water dispersible gel forming organic polymeric materials. Various optional components are also mentioned by Barford; namely, dyestuffs, perfume, water soluble fillers, water softening or chelating agents, solid water soluble acids, inert water insoluble inorganic or organic fillers, tablet lubricants, and agents having disinfecting or germicidal activity.
U.S. Pat. No. 4,460,490 to Barford, et al., discloses a freestanding lavatory cleansing block that comprises a shaped body formed of a slow dissolving cleaning composition containing a surface active agent and a tablet comprising a bleaching agent embedded in or adhered to the shaped body. The shaped body, according to the '490 patent, may be melt cast, tableted, or extruded, depending upon the geometry of the shaped body. The shaped body preferably comprises the aforesaid surface active agent and a solubility control agent, for example, a water soluble or water dispersible gel forming polymer, for example, chemically modified celluloses.
Ziek et al., U.S. Pat. No. 4,722,802, also discloses hydrated cellulosics to retard dissolution. In Ziek et al., the advantages of curing the resultant block are also discussed. Similarly, Bunczak et al., U.S. Pat. Nos. 4,911,858 and 4,911,859, disclosed very high molecular weight polyethylene oxide polymers together with guar gum and calcium salt to form a gelatin matrix that slows dissolution of the solid system.
Like Menke et al., U.S. Pat. No. 4,820,449, Jeffrey et al., U.S. Pat. No. 4,043,93 1, seeks slow dissolution through the use of mono- or di-alkanolamides of various aliphatic chain lengths while adding ethylene oxide/propylene oxide block copolymer surfactants with unspecified monomer ratios. Jeffrey, et al., discloses a lavatory cleansing block comprising a solid carrier base which is a mixture of two or more nonionic surface active agents, one of which is relatively insoluble in water and the other of which is relatively soluble in water. The lavatory block of Jeffrey may optionally include perfume, dyestuff, germicide, and fillers, the latter being for example, a water softener such as a alkali metal polyphosphate. The blocks of Jeffrey are made by tableting.
Polyethylene glycol, having a molecular weight of about 8000, is taught in U.S. Pat. No. 5,342,550, Burke et al. together with one or more fillers or binding agents for use in solid block compositions. Examples of acceptable binding agents disclosed include the water-soluble alkali metal and alkaline earth metal salts. The compositions also preferably comprise one or more additional ingredients such as, for example, cleaning agents, deodorizers or perfumes, bactericides, bacteriostats, hard water film inhibitors, stain inhibitors and dyes.
U.S. Pat. No. 4,438,015 to Huber discloses lavatory cleansing blocks comprising as a solid carrier base a mixture comprising a major proportion of a nonionic surface active compound and a minor proportion of a partially esterified copolymer of vinylmethyl ether and maleic anhydride (PVM/MA). The blocks of Huber are melt cast.
U.S. Pat. No. 4,229,410 to Kosti discloses a bacteriostatic toilet element comprising a water sensitive, water soluble or swellable binding agent and a bacteriostatic and/or deodorizing and/or coloring agent. Kosti's element may be melt cast or extruded.
As discussed above, surfactant cleansing blocks can be made by tablet forming methods, casting or extrusion as described for instance in U.S. Pat. Nos.: 4,043,931; 4,269,723; 4,460,490; 4,438,015; 4,722,802; 4,738,728; and 4,082,449. The surfactant in these cleansing blocks is released gradually over an extended period of time to clean the porcelain surface of the toilets.
Toilet bowl detergent compositions that are not blocks can also be used to form detergent solutions. There are a variety of dispensers that provide for controlled release. For example, U.S. Pat. No. 4,813.084, Buecheler et al., discloses a rim-block holder that can use granular compositions. Similarly, there are a multitude of "passive" dispensers, such as U.S. Pat. No. 4,462,121, Dirksing et al., that can use liquid or solid compositions to form the cleaning solution in the toilet tank.